Gear oil is typically used in transmissions, transfer cases, and differentials in automobiles, trucks, and other machinery. Gear oil is usually of a high viscosity in order to better protect the gears from wear, corrosion and thermal damages. In the absence of an oil pump, the gear oil can be picked up by a portion of the lowermost gears bathed in an oil sump and transferred to the rest of the gear train through the rotating action of the gears. A high viscosity gear oil, on the other hand, creates viscous drag and churning loss leading to inefficiencies in vehicle operation.